[Intel-gfx] [PATCH 1/7] drm: mark drm.debug-on-dyndbg as BROKEN for now

Jim Cromie
2022-11-11T22:17:41Z

drm.debug-on-dyndbg has a regression, due to a chicken-egg
initialization problem:

1- modprobe i915
i915 needs drm.ko, which is loaded 1st

2- "modprobe drm drm.debug=0x1ff" (virtual/implied)
drm.debug is set post-initialization, from boot-args etc

3- `modprobe i915` finishes

W/O drm.debug-on-dyndbg that just works, because all drm_dbg*
callsites use drm_debug_enabled() to check __drm_debug & DEM_UT_<CAT>
before printing.

But the whole point of drm.debug-on-dyndbg is to avoid that runtime
test, by enabling (at post-modinit) a static-key at each callsite in
the just-loaded module.

And since drm.ko is loaded before all dependent modules, none are
"just-loaded", and no drm.debug callsites are present yet, except
those in drm.ko itself.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
drivers/gpu/drm/Kconfig | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 34f5a092c99e..0d1e59e6bb7e 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -54,6 +54,7 @@ config DRM_DEBUG_MM
config DRM_USE_DYNAMIC_DEBUG
bool "use dynamic debug to implement drm.debug"
default y
+ depends on BROKEN # chicken-egg initial enable problem
depends on DRM
depends on DYNAMIC_DEBUG || DYNAMIC_DEBUG_CORE
depends on JUMP_LABEL
--
2.38.1